net: ravb: Fix lack of register setting after system resumed for Gen3

After system entered Suspend to RAM, registers setting of this
hardware is reset because the SoC will be turned off. On R-Car Gen3
(info->ccc_gac), ravb_ptp_init() is called in ravb_probe() only. So,
after system resumed, it lacks of the initial settings for ptp. So,
add ravb_ptp_{init,stop}() into ravb_{resume,suspend}().

Fixes: f5d7837f

 ("ravb: ptp: Add CONFIG mode support")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>